Automatic stoker



Jan. 14, 1941.' J. A. CASEY 2,228,947

AUTOMATIC STOKER Filed Aug. 24, 1957 (Inna/4211 44 til ill

atented Jan. 14, 1941 UNITED STATES PATENT OFFICE t Claims.

This invention relates to automatic stokers and it has for its general object the provision of a stoker chassis adapted'to be optionally employed with any of the several sizes of burner, to take coal by gravity from a hopper or by conveyor from a bin and to discharge ashes either into a pit or by means of one of several types ct conveyor.

Another object of the invention is the provision of an automatic stoker consisting fundamentally of a burner, coal tube, coal receiver and fan in which the receiver is adapted to be connected to a gravity discharging hopper or to a conveyor leading from a remote bin. p A further object of the invention relates to orientable conveyors alternatively provided, for feeding coal from the bin to the receiver either by way of the top or bottom, with driving means for said conveyors.

Still another object of the invention in a stoker of the type described is the provision of a fan which while drawing the main part of its air supply for the fuel blast from atmosphere is at the same time in a recurrent air circulation system which draws air from the coal tube and discharges it into the main blast to the burner.

Another object of the invention relates to an automatic stoker including in combination with the burner element a rotating ash scraper including an element cooperating to continually remove the marginal accumulation of ash overlying the edge of the burner and the novel construction of ring upon which the ash scraper is mounted.

A further object of the invention relates to non-clogging driving means for the ash scraper ring.

Other objects of the invention relate to the automatic stoker as above described in a combination with alternative types of ash conveyor.

In the drawing throughout the several figures of which the samecharacters of reference have been employed to designate identical parts:

Figure 1 is a side sectional view of an automatic stoker embodyingthe features of the present invention;

Figure 2 is a planview of the same partly in section;

Figure 3 is a plan view of the ash scraper ring parts being omitted;

Figure 4 is a side section showing details of construction of the ash scraper, ring.

Referring now' in detail *to the figures, the numeral i represents a base having the conventional leveling means 2 and to which is se cured the parts constituting the chassis 3; Said (ill. 110-45) chassis comprises a coal receiver t having'a substantially horizontal coal tube 5 secured to the front end thereof and in communication there'- with, the outer end of the coal tube being formed with an elbow 6 over which are mounted a plu- 5 rality of coaxial rings i which normally rest freely upon one another with draft louvers t in between. Said rings progressively flare so that the number tobe employed depends upon the diameter of the fire pot of the furnace in which m the burner is installed.

A screw conveyor ll extends through the coal tube 5 terminating substantially beneath the vertical axis of the burner and being suitably driven at its opposite end through a sprocket It, the 5 chassis being provided with an upwardly extending recess, housing said gear and which produces a hump ii on the inside of the coal receiver t; A fan I2 is suitably mounted with respect to the coal receiver 4, said fan taking in an air centrally through a damper controlling opening it and discharging it peripherally through a conduit M which is not in communication with the coal receiver, but which communicates with an outer tubular casing l5 which surrounds the coal tube 5. The casing i5 terminates in an albow IG coaxialwith the burner and surrounding the lowermost of the rings 1!. Said elbow is formed with a wide inturned flange ii. To the inner edge of the flange it is bolted or otherwise secured an annular fitting it formed with an annular channel iii. In the channel is freely seated an inverted bell-shaped casting 20 which extends beyond the uppermost ring and terminates in a wide flange or collar 2i having an annular rabbet 5| forming a peripheral track on which rests the matching rabbet tt oi. an outer rotating ash lip 53.

A ring 33 freely seats upon the outer peripheral portion of the flange ll of the elbow It, being rotatable thereabout. Said ring is provided with a.

bar 34 having an upstanding end 35 which moves concentrically with respect to the burner, and being attached to the ash lip 53, the latter ro tating with said ring. The function of the rotating ash lip is to break the marginal portion of the ashes off from the ash heap on top of the" fuel in the burner. and to let it drop by gravity into the pit 32. This is a continuous rotating operation whilever the stoker is operating.

The ring 33 seats on a flange ll of the elbow l6 by means of a plurality of inwardly extending spaced lugs 36 which rest upon the flange I1.

Said lugs have inwardly sloping top faces 31 which shed ashes which may collect upon them,

and side faces 38 which sweep ashes off of the flange H. The ring 33 does not fit closelyagainst the elbow I6, but is spaced therefrom by a narrow annular space 39, said space providing an annular passage for the ashes to drop through which are dislodged from the flange IT by the lugs 36. It will be understood by the description 01' the ring 33 that it not only freely rotates, but also is capable of slight shifting motion in the plane of its rotation permitted by the space 39. Due to this free fit it is not necessary to machine the ring 33 so that it may be cheaply cast.

The ring 33 is provided with a lower peripherally extending flange 40 formed with gear teeth 4|. (See Figure 2.) The ring 33 is rotated by means of a shaft 42 driven from the motor 43 and having a worm drive 44 in engagement with the gear teeth 4|, said worm drive bing in the form of a section of a screw propeller, the object being to convey ashes away from the immediate vicinity of the gear teeth. This form of drive necessitates that the gear teeth be uni-directionally inclined and made in the form of knobs which freely fit the space between the spirals of the screw, being driven thereby. It will be understood that the ring 33 is in position to be covered with ashes from time to time so that some special driving connection is necessary to prevent its becoming jammed with ashes. The loose relation of the knob-like teeth 4| with the conveyor-shaped worm drive 44 ensures that there will be no jamming while the specliic shape of the worm drive acts in effect to convey the ashes away from the gear connection and to keep it clean. It will be understood that the worm drive 44 rotates in a direction to lift the ring 33 rather than in an opposite direction and thusminimizes the friction between the parts. It may happen that from time to time the ring 33 will chatter against its seat to safeguard which a lubricating cup 45 is provided with a tube 43 which opens on the seating face of the flange l1 and thus lubricates the bearing joint between the elbow and the ring 33. Experience has shown that this lubricating cup 45 does not have to be attended more than once or twice in a season.

The air blast discharged from the periphery of the fan passes through the casing I! upwardly between the burner rings on the one hand and the wall of the elbow IS, the fitting l8 and the casting 29 on the other. The blast enters the burner through the annular cracks between the rings. In order to avoid back draft the lower rings are so shaped that the annular cracks between them are inclined upwardly at their inner portions so that the entering air blows upwardly toward the burning surface of the fue Also the conduit I4 is placed into communication with the burner chamber below the bottom of the fuel body within the burner, by means of one "or more small apertures 22 which equalizesthe pressure below and within the burner chamber. The central fan inlet opening I3 is connected by 'a manifold 23 with the chamber of the receiver 4 v and incidentally with the coal tube 5. The fan draws its main body of air from atmosphere through theopening 24 in the manifold 23, but

} maintains a slight degree ,of sub-atmospheric pressure on the-air within the coal tube'5. This assures that in the event of back pressure due to the explosion of combustible gases within the burner, said gases will be drawn through the coal tube through the opening 3| of the coal receiver 4, through the manifold 23 and back to the fan 'sure upon the conveyor 9.

to commingle with the blast which supplies draft to the burner.

' Figure 1 shows that the coal is conveyed from a bin at some distance from the coal receiver 4. A pipe 25 is secured at an open boss 26 projecting from the lower portion of the receiver 4.

Said pipe leads to the coal bin. A screw conveyor 21 extends through the pipe and is operatively connected to the sprocket I0. Said screw conveyor is preferably formed of sections. Three are shown in the drawing designated consecutively by the numerals 29, 29 and 30. The screws in these sections are of different pitch, that in the section closest to the bin being of steepest pitch and the pitch becoming less steep, and the spaces' faster adjacent the receiver 4 than at the bin end. of the conveyor so that the column of coal is.

never jammed by the weight or mass of coal in the end of said column near the coal receiver. The nature of the pitch of the conveyor 21 as described also prevents clogging of the coal supply through the weight of the coal being lifted up the inclined side of the hump The flow of coal is further facilitated by the shape of the coal receiver which flares progressively from the outlet of the coal pipe 25.

As the coal cascades over the peak of the hump down to the anterior of the conveyor 9, the particles will be relatively separate and any dust or small granules will be in a loose and easily dissipated condition. It would not do to have the back draft of the coal tube 5 impinge upon opening 3| by which the manifold 23 communicates with the coal receiver is placed close to the forward wall of the coal receiver and as far as possible from the region at which the coal cascades over the hump so as to avoid entraining loose dust and debris of the coal.

In operation, coal is conveyed from the bin by means of the screw conveyor 21, lifted over the hump II by the thrust of the said screw conveyor and cascades down upon the anterior end of the conveyor 9 within the ,coal tube 5. The coal receiver 4 may become partially filled through the action of the conveyor 21. Goal is delivered by the conveyor 9 into the lower part 'of the burner chamber and pushed upward by the thrust of the conveyor spreading out as the burner chamber flares, this preventing back pres- Combustion takes place adjacent the surface of the mass of coal in the burner the ashes falling upon the collar 2| and ash ring 41. Ashes are continually scraped away by meansof the bar 34 on the ash scraper ring 33. The fan draws in atmospheric air through the opening 24' in-the manifold 23 and through the damper'controlled opening l3 and also draws in a small proportion of air through the coal tube 5, the coal receiver 4, the opening 3| and by way of the manifold 23 the air is forced through the conduit l4, casing i5 and the air chamber surrounding the burner, entering the burner through the cracks of the It is clear that as the ring i and also entering below the mass of fuel in the burner through the apertures 22. As the ashes accumulate they may be removed from the pit 32 in any usual or convenient manner. A plug 50 is provided in the bottom of theelbow t which may be removed permitting dust, etc., to be blown out through the port 14 which the plug fill closes, said plug when screwed in butts against the boss at the bottom of the elbow t lifting the elbow and rings, tightening the rings together. This is of great convenience in adjusting the rings after installing, for since the upper ring is supported by thebell-shaped casting the bottom of which rests in a seal of sand or etc., in the channel 19, it may be that the top ring will be unduly spaced from the rings below when the installation is first effected and before adjustment.

While I have in the above description disclosed what I believe to be preferred and practical embodiments of my invention, it will be understood to those skilled in the art that the specific details and arrangements of parts as shown and de-,

scribed are by way of example and not to be construed as limiting the scope of protection of the apparatus as claimed,

What I claim is:

'1. Automatic stoker comprising a coal tube formed with an upturned elbow at one end,,,a burner connectedto said elbow comprising a plurality of spaced rings seated upon one another in inverted conical formation defining a fuel chamber, an air condult'surrounding said coal tube having an upturned elbow co-axial with the elbow of said. coal tube and terminating in a horizontal flange, a fitting secured to the inner margin of said-flange leavingthe outer margin exposed, said fitting having a channel, a flaring jacket having its lower end' seated in said channel and its upper end connected to said burner intermeshed with said teeth for driving said ring.

2. Automatic stoker as claimed in claim 1, the driving means forgsaid ring comprising a shaft, a worm on said shaft formed as a screw conveyor and the teeth on said ring being pins extending into the helical channel of said screw conveyor.

3. Automatic stoker as claimed in claim 1, the lugs on said ring having inclined side faces servmg to scrape ashes from the flange on which I said lugs rest into the passages constituted by the clearance between said ring and elbow.

4. Automatic stoker comprising a coal tube formed with an upturned elbow at one end, a

burner connected to said elbow comprising a plurality-of spaced rings seated upon one another in inverted conical formation defining a fuel chamber, the topmost ring comprising an annular collar with a peripheral rabbet forming a track, an ash lip rotatably seated upon said track having its upper face substantially in the plane of the upper face of said collar and forming an outward continuation of said collar, a driving ring mounted adjacent the lower part of said burner, and means arising from said driving ring and secured to said ash lip for rotating the latter with said driving ring.

JAMES A. CASEY. 

